Supported catalyst paraffin alkylation process



July 17, 1962 A.scHR1EsHE1M l-:T AL 3,045,056

SUPPORTED CATALYST PARAFF'IN ALKYLATION PROCESS Filed Nov. :5, 195e AIon Schriesheim George R. Gilber Inventors By y M AHorney LIGHTER HYDROCARBON FEED kUnited kStates Patent 5 SUPPRTED CATALYT PARAFFIN ALKYLATIUN PROCESS Alan Schriesheim, Fords, and George R. Gilbert, Elizabeth, NJ., assignors to Esso Research and Engineering Company, a corporation of Delaware Filed Nov. 3, 1958, Ser. No. 771,319 6 Claims. (Cl. 260-683.53)

carbon atoms in the presence of aluminum bromide and a promoter support under conditions that favor the production of high yields of branched chain paraffin hydrocarbons of 5 to 7 carbon atoms.

A major problem in petroleum refining is to secure from the hydrocarbon sources available a sufficient quantity of high octane rating hydrocarbons boiling in the motor fuel range to satisfy the demands of modern high compression engines.A Processes for producing the high octane components must not be too costly and must have a reasonable degree of versatility. Hertofore a number of processes have been available which use C3 and C4 .petroleum fractions from various sources such as natural gasoline plants, distillate recovery plants and various petroleum renery streams, and which convert those fractions to motor fuel components by polymerization reactions or by alkylation reactions. For example, isobutane can be reacted with butylene in the presence of sulfuric acid to give a branched-chain 8-carbon-atom alkylate. Also butylene can be polymerized to a C8 unsaturated hydrocarbon which upon hydrogenation will give isooctane. These processes have some disadvantages in that they require a number of separate operations and in that they necessitate the use of olelins, which are usually in relatively limited supply.

It has now been found that, by the use of a promoted aluminum bromide catalyst, butanes and/ or pentanes can be reacted directly with higher paraflin hydrocarbons to give good yields of C5 to C7 branched chain hydrocarbons of high octane rating, provided certain speciiic conditions are employed. It has previously been proposed to conduct reactions of this type but yields have been low, reaction rates have been uneconomic and satisfactory product distribution has not been obtained.

In accordance with the present invention, a` parain hydrocarbon of from 6 to 18 carbon atoms is reacted with a large excess of a butane or a pentane, preferably isobutane, employing as a catalyst AlBr5 supported on or associated with calcined bauxite, at temperatures in the range of from about 30 to about 140" F. and at pressures su'icient to keep the reacting hydrocarbons in the liquid phase. The products of the reaction are saturated branched chain paraflin hydrocarbons predominantly in the C5 to C7 range. The preferred temperature range is from about 50 to about 120 F.

The nature and objects of this invention and the manner in which the invention can be practiced will be more readily understood when reference is made to the accompanying drawing yin which the single FIGURE is a schematic flow plan of one process for practicing the invention.

The process will be described with particular reference to the use of isobutane as the lighter component. Referring to the drawing in detail, a suitable butane feed stream containing at least initially a major proportion of isobutane is obtained by means of line 11 from a suitable source. A portion of the stream is conducted Via line 11a through an aluminum bromide pick-up vessel 12 to dissolve aluminum bromide in a portion of the streamthat is conducted to the reaction Zone. The remaindergof the feed stream is combined -with the effluent leaving the pick-up vessel via line 13 and is conducted Vinto a reaction zone 15. The latter zone contains one or more beds of calcined bauxite saturated with aluminum bromide.

A stream of a higher parain hydrocarbon, as for example heptane, octane, dodecane or cetane, or of mixtures containing the higher parafiins, is conducted into the reaction zone by means of line 16. Preferably the stream enters the reaction Zone at a plurality of spaced points, 16a, 1619, etc., so as to insure as high a ratio as possible of isobutane to vhigher paraiin at any particular point in the reaction zone.

The reaction product leaves the reaction zone through line 18 and is conducted into an initial separation zone 20 wherein light materials, including unreacted isobutane and normal butane, are removed overhead andrecycled to the reaction zone by means of line 21. Hydrogen bromide, if present, will also be recycled via line 211. The heavier material, `including C5 hydrocarbons and higher, is conducted by means of line 22 into a product separation zone 24 wherein C5 to C7 hydrocarbons arel re-V i moved overhead by means of line 2S while heavier material comprising C8 hydrocarbons and higher as well as any aluminum bromide that has been removed from the reaction zone is recycled to` the reaction zone by means of line 26. If desired, conditions can be adjusted in separation zone 24 to include normal heptane in the heavier material recycled through line 26, while including the C7 branched chain isomers in overhead line 25.

In place of isobutane the feed in line 11 may comprise normal butane, in which case no higher hydrocarbon feed stock will be sent initially to the reaction zone |but the butane will be recycled through' line 18, zone 20 and line 21 until a considerable amount of the butane has been isomerized to isobutane. The process may then continue in the manner already described, the recycle isobutane being sufficient to make the desired reaction proceed while the fresh butane feed becomes isomerized to isobutane in the reactor.

A number of factors in the process of the present invention are critical to its operation in order that proper distribution of the products may be obtained. For example, at temperatures above about F. considerable cracking occurs and the principal products are propane and lighter materials. Also it has been established that aluminum bromide alone or even in the presence of conventional hydrogen halide promoters such as hydrogen bromide, in the absence of the support, is very much less active than the catalyst system of the present invention. Furthermore in order for the reaction to proceed satisfactorily it is necessary that sufficient aluminum bromide be present not only to saturate the support under the reaction conditions employed but also to leave at least a small amount dissolved in the reacting hydrocarbons.

A mixed catalyst in which a portion of the aluminum bromide is replaced with aluminum chloride may be used provided that at least some aluminum bromide is present in the reacting hydrocarbons over and above that which is adsorbed on the support.

Although the reaction may proceed in the absence of hydrogen bromide promoter it is preferred that it be used as an auxiliary promoter in addition to the calcined bauxite. A range of from about 0.1 to 8% or more of HBr by weight based on total feed may be used, while from about 0.3 to about is preferred. When hydrogen bromide is employed it is introduced into the reaction zone by means of line 17 and will be recycled to the reaction zone along with unreacted butanes by means of line 21.

Although the process as described in conjunction with the drawing contemplates downtlow of the stream through the catalyst bed, which is preferred, upow can also be used. Also in place of a tixed bed process, a moving bed of catalyst could be used. Alternatively, a slurry type of operation could be employed 4wherein a suspension of catalyst is maintained in the reacting hydrocarbons, the slurry being stirred in the reactor with suitable mechanical stirring means or recirculated through the reactor by pumping means. Where slurry operation is used, the slurry is removed from the reactor at the end of the reaction period, in the case of batch operation, or as a fraction of the circulating stream in the case of continuous operation, and sent to suitable separation equipment to separate the catalyst from the hydrocarbons. The separation equipment may comprise a simple settling tank, a centrifuge, or a filter, for example, or suitable combinations of such means.

It is preferred that the minimum mol ratio of isobutane and/or isopentane to higher paran be about 3 to 1 but should preferably be no higher than about l2 to 1. If sufficient iso-C4 is not present in the reaction zone to effect alkylation of the materials obtained when a higher paran or other higher product of the reaction is cracked by the catalyst, catalyst sludging will result. The feed stock must be essentially free of aromatic hydrocarbons and not more than about 0.02% of such material should be present. .An added advantage of the catalysts of the present invention is that naphthene hydrocarbons may be tolerated in the feed stock up to about 20 volume percent. With increased naphthene content the reaction severity must be increased somewhat as compared to a reaction in the absence of naphthenes. This may be accomplished by raising the temperature and/or lowering the feed rate, for example.

Feed rates may vary from about 0.3 to about 2 v./hr./v. (liquid volume of total feed per hour per volume of total catalyst plus support) the higher feed rates being preferred when little or no naphthenes are present.

To remove aromatics from the feed stock conventional techniques may be employed such as solvent extraction, hydrogenation, acid treating and the like, as well as treatment with selective adsorbents such as molecular sieve zeolites. It is not necessary that the higher hydrocarbons used be individual hydrocarbons such as heptane or octane or cetane, for example, but mixtures may be used, such as a petroleum fraction containing parainic hydrocarbons in the range of 6 to 18 carbon atoms. A1- though, as stated, hexane is one of the higher hydrocarbons that may be used, it is preferred to employ heptane or higher. Essentially the same product distribution is obtained with hexane as with heptane but the reaction rate is lower by a factor of about 3. Other sources of the higher paraffin hydrocarbons for the reaction include light virgin naphthas, and parafiin rainates from the extraction of hydroforrned petroleum fractions.

A calcined bauxite that may be employed as the catalyst promoter in the present invention can be obtained commercially under the trade name Porocel Before the bauxite is used it should be dehydrated. A suitable pretreatment for this purpose involves heating for from about 3 to 5 hours at 1100" to 1200" F.

At the start of the process the calcined bauxite may be saturated with aluminum bromide and then placed in the reaction zone, or, alternatively, the bauxite alone may be placed in the reaction zone and then saturated with aluminum bromide carried in with a portion of the feed. Another method of preparation is to mix the aluminum halide with the support and to heat the mixture to effect impregnation. If desired, loosely held aluminum halide may be removed from the catalyst mass by heating the mass and passing through it a gas such as carbon dioxide, methane, hydrogen or nitrogen.

Alternatively the support may be impregnated by dissolving the aluminum halide in a suitable solvent such as ethylene dichloride or dioxane, for example, and the porous carrier impregnated with this solution, followed by heating to remove the solvent and loosely held aluminum halide. Still another alternative is to employ a powdered support or promoter, mix the aluminum halide with it, and compress the mixture into pellets.

The following examples serve to illustrate the practice of the present invention.

EXAMPLE 1 Comparative tests were made in which in each instance a mixture of 160 cc. of isobutane and 40 cc. of a normal heptane feed (containing n-C, and 5% of methylcyclohexane) was stirred for 3 hours at 72 F. with one of the catalyst systems identified in Table I.

It will be seen from the results of these comparative tests that aluminum bromide alone, or even in the presence of hydrogen bromide, was not effective in producing the desired reaction. In both of these instances the major proportion of the reaction products comprised C7 hydrocarbons. The aluminum bromide merely served as an isomeiization catalyst. On the other hand, in the tests in which aluminum bromide and Porocel either alone or in conjunction with hydrogen bromide were employed as the catalyst, considerable yields of C5 and C, isomers were obtained.

EXAMPLE 2 In a manner similar to that employed in Example 1 comparative tests were made with a number of other supports or promoters in addition to Porocel. These included Fe203 and FeCl3 which are known to have high activity for promoting isomerization reactions. The results obtained are shown in Table II.

mide, in the ratio of 24 grams of halide to 47 grams of Porocel. The metal halides used were aluminum chloride, aluminum iodide, aluminum lluoride, bismuth trichloride, ferrie chloride, tin tetrachloride and titanium tetrachloride. The concentration of aluminum fluoride on Porocel was slightly lower than with the other metal halides. None of these metal halides Was found to have any apparent activity for the desired reaction under the conditions employed.

' EXAMPLE L1 In another group of tests the effect of naphthenes on the reaction was determined. Using the catalyst system of Test 3 of Example 1 and the same reacting hydrocarbon mixture as in that test, but varying the percentage of naphthenes, it was found that as the concentration of methylcyclohexane in the normal heptane feed was in creased from 1 volume percent to V20 volume percent the relative rate of conversion of heptane to C5 and C6 branched chain hydrocarbons was reduced by a factor of 3. It was also found that the inhibiting effect of naphthenes on the reaction can be overcome to some extent by raising the temperature. Thus, raising the reaction temperature from 100 F. to 115 F. when 8% of methyl cyclohexane was present brought about a doubling of the reaction rate, as measured by the weight percent f C7 hydrocarbons in the C+ product after various reaction times. This is shown in Table III.

5 l6 TABLE II EXAMPLE 5- In another series of tests conducted in the same man- Tests Tes Test Test? Tests ner as described in Example 1, the effect of thefratio of isobutane to heptane on the yield of C5 to C7 branched Cttls, 5 chain hydrocarbons was determined. The catalyst n grams 23.6 23.6 23.6 23.6 23.6 these tests consisted of 20 grams of aluminum bromide, IQL" Porocel Fem F901 m A120 39 grams of aluminum chloride and 119 grams of Poropromoter.- 47.2 47.2 t 11.8 47.2 47.2 ce1. The reaction temperature was F., the pressure Analysis of 05+ was 300 p.s.i.g. and each reaction consumed 2 hours, the rgitt, 10 normal heptane being added gradually during the entire percent; react1on period. The results obtained are given in Table lsfC (lig IV and show that the yield of C5+ hydrocarbons increased as the ratio of isobutane to heptane was increased 25.6 1.5 1.8 2 1 L8 over a mol ratio range of about 3 to 1 to about 10 to 1.

l5 133% ti 3'8 t1 3:3 TABLE 1V Total can." 15.7 1 9 0 8 1.1 0.4 EEC 0f ISObLlal1e-O Hepfale RIZO 0n isoy 56.5 93.2 62.9 46.1 65.0 n-C1 2.2 3.4 34.5 50.7 22.8 Feed Composition:

20 Grams, Isobutane 285 285 285 Tota1C7--. 58.7 96.6 97.4 96.8 97.8 Grams, n-Heptane 170 85 33 Ylelds, Wt. percent on Heptane Feed:

C; and less 6 10 36 1 Allos-90%, rezos-10%. 05+ 122 153 170 It will be seen that neither alumina, ferrie chloride nor FeZOs was effective in promoting the desired reaction. The alumina used in the above tests Was found to be of sgi; 4,2% 3?: the eta formi In each case the principal product comprised 1C, hydrocarbons although some isomerization of 40'2 489 44- the latter had occurred. 21.1 24.2 12. EXAMPIE 3 Y 30 l 1.4 1.4 0. In a similar manner, another series of tests were `run 22'5 25'6 13' at temperatures of 72 to 75 F. with the same feed com- 23.9 22.1 30. position and the same feed-to-catalyst support ratio as in 9'1 L1' 12' Example 1 (200 cc. total feed to 47 fgrams of Porocel) 33.0 23.2 42. using various metal halides other than laluminum bro- 35 EXAMPLE 6 Employing the same catalyst mixture as was used in Example 5, tests were made in which normal octane, normal cetane and normal octadecane were lsubstituted for the normal heptane. F. inthe case of yoctadecane and 100 F. in the other runs. The reaction pressure in each instance was 300 p.s.i.g. :and 2-hour reaction times were used. It lWill be seen fronrthe data in Table V that the product distribution was essentially the same regardless of the higher parat-lin used. TABLE V Comparison of Reactions With Hydrocarbons of 7 to 18 Carbon Atoms Feed Composition Heptane Octane Cetane Octadecane 342 Grams, Isobutane 285 285 285 48. 4 Grams, Heavier Paratiin. 85 87. 5 47. 5 Yields, Wt. Percent on Heavy ier Paran:

C3 and less 10 9 6 23 05+ 153 155 188 190 Analysis of 05+ Product,

Weight Percent: i

iso-C5 42. 1 48.0 35. 7 42. 4 11-05 6. 8 8. 6 6.3 9. 2

Total C5 48. 9` 56. 6 42.0 l 51. 6

Total Cs 25. 6 25.6 22. 4 27.3

iso-C7 22. 1 9. 7 9. 6 7.19 n-C; 1. 1 0.5 0. 5

Total C1 23. 2 10.2 10. 1 7. 9

EXAMPLE 7 A catalystcomposition comprising Porocel and aluminum bromide in a 1 to 1 Weight ratio of A1Br3 to support was tested in a continuous pilot unit consisting of a The reaction temperature wasl jacketed reactor provided with a Amechanical stirrer and with a settling chamber to permit slurry operation. Reaction conditions were 100 F. fand 150 p.s.i.g. pressure. A feed mixture of normal heptane and isobutane which gave about 70 volume percent of isobu-tane in the reactor was passed through the reactor at a space velocity of about 0.05 volume of heptane per hour per volume of the reactor. As the catalyst occupied about 25 percent of the reactor volume this feed rate corresponded to about 0.2 v./hr./v. of catalyst. ously added to the reaction zone as a solution in the iso-- butane in suicient quantity to constitute a to l0 weight percent solution based on total feed. Hydrogen bromide was also added at the rate of 1 to 5 weight percent based on feed. The total liquid product from the reactor was scrubbed with percent caustic to remove aluminum bromide and H12-r, then dried, debutanizcd and analyzed. Continuous catalyst activity was observed -for 150 to 200 hours operation, with good yields, of the order of 135 to 145 volume percent of C54- hydrocarbons, based on the normal heptane. A similar continuous run with cetane as the higher paraiiin lfed, using the same reaction conditions, the same catalyst mixture and the same ratios of isobutane to higher parain, gave yields of the order of 250 to 260 volume percent of C54- hydrocarbons, based on the cetane. In `both runs, i'.e. with heptane and with cetane, the ratio of C5 to CG hydrocarbons was about 2 to 1.

Other studies of continuous operation established that in order to maintain catalyst activity it is necessary to have present in `the reaction zone suicient aluminum bromide to furnish aluminum bromide in solution in Ithe reacting hydrocarbons over and above the quantity required to satisfy the total adsorption capacity of the calcined bauxite. it is preferred that suicient aluminum bromide be dissolved in at least one of the entering streams of reacting hydrocarbons so `that at least 0.05 weight percent of aluminum bromide will be present in the products leaving the reaction zone.

Certain modifications of the process outlined hereinbefore will occur -to those skilled in the art. Such modications are contemplated within fthe scope of the present invention. For example, if rthe yield of C5 hydrocarbons is larger in proportion to the C5 hydrocarbons than is desired, the product may be distilled to separate a C5 cut which may `then be used in a conventional alkylation step with an olefin such as ethylene, propylene or a butene, employing the usual alkylation catalysts such as sulfuric acid, phosphoric acid, hydrogen uoride, or an aluminum halide. Alternatively, the C5 cut can be sent to a second reaction zone of the type herein described for reaction with higher normal parain hydrocarbons.

It is to be understood that this invention is not to be limited to the specific embodiments and examples herein described and presented but that its scope is to be determined solely by the claims appended hereto.

What is claimed is:

l. A liquid phase process for the preparation of high oc- Aluminurn bromide was continul To ensure this in a continuous oper-ation tane naphtha components consisting largely of branched chain paraiiin hydrocarbons c'f '5 to 7 carbon atoms which comprises reacting a minor proportion of a straight chain parafn hydrocarbon of from '6 to 18 carbon atoms with a major proportion of a lighter hydrocarbon selected from the group consisting of butanes and pentanes, at temperatures no higher than about F., in a reaction zone in the presence of a catalyst comprising aluminum bromide'and calcined bauxite, supplying to the reaction zone sufficient aluminum bromide to furnish at least 0.05 weight percent of aluminum bromide in solution in the reacting hydrocarbons over and above the quantity required to satisfy the total adsorption capacity of the calcined bauxite.

2. Process as defined by claim 1 wherein reacting hydrocarbons are continuously conducted into said reaction zone and reaction products are continuously removed from said reaction zone and wherein suiiicient aluminum bromide is dissolved in at least one entering stream of reacting hydrocarbons so that at least 0.05 Weight percent of aluminum bromide is present in the products removed from said reaction zone.

3. Process as defined by claim l wherein from about 0.1 to about 8 percent of hydrogen bromide, based on the reacting hydrocarbons, is present in the reaction zone.

4. Process as delined by claim l wherein Vthe mol ratio of said lighter hydrocarbon selected from the group consisting of butanes and pentanes to said hydrocarbon of from 6 to 18 carbon atoms in the reaction zone is in the range of from about 3 to 1 to about 12 to 1.

5. Process as defined by claim l wherein naphthenic hydrocarbons are present in said reaction zone.

6. A process for the preparation of high octane naphtha components consisting largely of branched chain parain hydrocarbons of 5 to 7 carbon atoms which comprises reacting a straight chain parain hydrocarbon of from 6 to 18 carbon atoms with a lighter hydrocarbon selected from the group consisting of butanes and pentanes, wherein the mol ratio of said lighter hydrocarbons to said straight chain paratiin hydrocarbon is in the range of from about 3:1 to about 12:1, at temperatures in the range of about 50 to 120 F., in a reaction zone in the presence of a catalyst comprising aluminum bromide and calcined bauxite, supplying to the reaction zone suicient aluminum bromide to furnish atleast 0.05 weight percent of aluminum bromide in solution in the reacting hydrocarbons over and above the quantity required to satisfy the total adsorption capacity of the calcined bauxite.

References Cited in the tile of this patent UNITED STATES PATENTS 2,349,458 Owen et al May 23, 1944 2,370,144 Burk Feb. 27, 1945 2,401,925 Gorin lune 1l, 1946 2,415,061 de Simo et al Ian. 28, 1947 2,506,720 .Tones May 9, 1950 2,971,037 Gilbert et al Feb. 7, 1961 

1. A LIQUID PHASE PROCESS FOR THE PREPARATION OF HIGH OCTANE NAPHTHA COMPONENTS CONSISTING LARGELY OF BRANCHED CHAIN PARAFFIN HYDROCARBONS OF 5 TO 7 CARBON ATOMS WHICH COMPRISES REACTING A MINOR PROPORTION OF A STRAIGHT CHAIN PARAFFIN HYDROCARBON OF FROM 6 TO 18 CARBON ATOMS WITH A MAJOR PROPORTION OF A LIGHTER HYDROCARBON SELECTED FROM THE GROUP CONSISTING OF BUTANES AND PENTANES, AT TEMPERATURES NO HIGHER THAN ABOUT 140*F., IN A REACTION ZONE IN THE PRESENCE OF A CATALYST COMPRISING ALUMINUM BROMIDE AND CALCINED BAUXITE, SUPPLYING TO THE REACTION ZONE SUFFICIENT ALUMINUM BROMIDE TO FURNISH AT LEAST 0.05 WEIGHT PERCENT OF ALUMINUM BROMIDE IN SOLUTION IN THE REACTING HYDROCARBONS OVER AND ABOVE THE QUANTITY REQUIRED TO SATISFY THE TOTAL ADSORPTION CAPACITY OF THE CALCINED BAUXITE.. 